Is it permissible for the husband to seek divorce from his wife due to his inability to accept her short stature after marriage, knowing that she is pregnant and he feels guilty towards her?

The root of the problem is that you did not allow the fiancé a full, lawful viewing. You made a mistake when you completed the marriage despite feeling aversion. The real problem is that your wife loves you, fulfills your rights, and has gone beyond that, and she has conceived from you, and her life has turned into hell. Since you made a mistake, you must bear part of the consequences, which are in three directions: 1. Try to coexist with her and endure until the baby arrives, as your feelings might change. 2. If circumstances permit, keep her and marry another woman you desire, while taking care of your children and avoiding divorce. 3. If the previous solutions do not succeed and your hatred increases, then divorce is legislated for such a situation, and each of you may find happiness with another partner. If good companionship becomes impossible, then divorce is the solution.

Try to be insightful and think carefully, do not rush, and turn to Allah.

Remember the words of Allah the Almighty: (And live with them honorably. If you dislike them, it may be that you dislike a thing and Allah brings through it much good.) An-Nisa/19. And His words: (And it may be that you dislike a thing which is good for you.) Al-Baqarah/216. And the words of the Messenger of Allah, peace and blessings be upon him: (A believing man should not hate a believing woman; if he dislikes one of her characteristics, he will be pleased with another.) Narrated by Muslim (1469), meaning a believer should not detest a believing woman; if he dislikes one of her characteristics, he will find another praiseworthy one in her.